Study on the regulation of lipid signaling in pancreatic β-cells and the pathogenesis of diabetes mellitus

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Diacylglycerol kinases (DGK) phosphorylate diacylglycerol (DAG) to phosphatidic acid and strictly regulate the intracellular level of these lipid molecules. The expression of type I DGK (DGKαand γ) was detected in mouse pancreatic islets and the β-cell line MIN6. A specific type I DGK inhibitor inhibited insulin secretions and Ca2+concentration ([Ca2+]i) in MIN6 cells. Moreover, DGKαand γdoubleknockdown by siRNA led to significant decreases in insulin secretions. A membrane permeable DAG analog also inhibited [Ca2+]ielevations in MIN6 cells. These results suggest that DGKαand γare present in β-cells, and that DAG accumulation in β-cells resulting from hypofunction of these DGK isoforms leads to a decrease in [Ca2+]i,thereby reducing insulin secretion. Type I DGK could be a novel therapeutic target for diabetes mellitus.